Zika virus infection induces ultrastructural alterations, mitochondrial dysfunction and oxidative stress in human trophoblast HTR-8/SVneo

Background Zika fever gained importance in Brazil in 2015 due to its association with congenital syndrome. Although Zika virus (ZIKV) crosses the placenta and infects the fetus, its pathogenesis remains incompletely understood. This study investigated the effects of ZIKV infection in HTR-8/SVneo trophoblast cells. Methods Cells were infected with ZIKV (MOI 0.1, 0.2, or 1) or Mock control for 24 or 48 hours. Infection rate and viability were assessed by immunofluorescence and flow cytometry. Ultrastructural changes were analyzed by transmission electron microscopy. Mitochondrial membrane potential was evaluated by flow cytometry. Gene expression related to mitochondrial dynamics, antioxidant response ( sod, cat, nrf2 ), was analyzed by RT-qPCR. Protein expression (SOD, CAT, NRF2), enzymatic activities (SOD, CAT), and oxidative damage markers (8-OHdG, MDA, NO) were assessed by immunofluorescence and/or colorimetric assays. Results MOI 1 for 24 hours produced the highest NS1 expression and infection rate (62.53%) and higher viability (89% vs. 28.1%), establishing this as the optimal condition. Infected cells exhibited mitochondrial damage, including ruptured membranes and loss of cristae, dilated endoplasmic reticulum, clusters of virus-like particles, and vesicle secretion. Mitochondrial membrane potential was reduced, along with decreased transcripts of genes involved in mitochondrial dynamics. Although sod, cat , and nrf2 transcripts were reduced, protein immunolabeling and SOD activity were increased, whereas CAT activity was decreased. Elevated levels of 8-OHdG, MDA, and NO confirmed oxidative stress. Conclusion ZIKV infection induces mitochondrial dysfunction, oxidative stress, and impaired mitophagy in HTR-8/SVneo trophoblast cells, highlighting mitochondrial dysfunction as a major component of the cellular response to ZIKV infection in trophoblast cells.